The invention relates to a method and apparatus for automatically milking a dairy animal, in particular a cow, wherein a number of the milk""s characteristics are monitored as the milking proceeds and the process is terminated or the milk is diverted if an abnormality is detected or a predetermined norm or parameter is reached.
Such a method and device are known from the International Application No. PCT/US99/18742, International Publication No. WO 00/18218, of Gompper et al, published Apr. 6, 2000, for a milk flow monitor and milker unit detacher. Although in such application numerous possibilities are described with respect to the moment when milking by means of a teat cup is stopped, at the present moment there appears still to be a need for a method and a device by means of which it is possible to determine for each dairy animal individually the moment when milking can be stopped, so that a dairy animal can optimally be milked with respect to inter alia udder health and the like.
It is an object of the invention to supply the above need.
For that purpose, according to a first aspect of the invention, a method of the above-described type comprises deactivation of a teat cup when a deactivation threshold value is reached on a milk characteristic being monitored, such threshold value being arrived at based on, at least in part, the value of a milking parameter. Due to the fact that the deactivation threshold is determined at least partially based on the value of the milking parameter, the deactivation threshold can be adapted to the present momentary situation and the values of the milking parameter measured at the moment can be taken into account. This provides a considerable improvement relative to the existing pre-set deactivation thresholds.
The milking parameter is preferably selected from a group consisting of milk flow, milk yield, milk temperature, electric conductivity of the milk, fat content of the milk, protein content of the milk, cell count of the milk, intervals between milk gushes, duration of the milk gushes, and the peak and off-peak values of the mentioned milking parameters. Although other parameters may also be applied, these parameters appear to be the most efficient ones for determining the deactivation threshold.
It is particularly advantageous when, for the value of the milking parameter, an average value is selected. Due to this, fluctuations or temporary perturbations present by nature in the measured values are averaged, and a more accurate determination of the deactivation threshold becomes possible.
In an embodiment of a method according to the invention the method comprises the step of recording in a step (a) a starting time from which the average value of the milking parameter is determined. As a starting time from which the average value of the milking parameter is preferably determined the starting point of time when the milk flow in step (a) starts. In some cases the selected milking parameter shows strongly fluctuating values at the beginning of the start of the milk flow, so that it is advantageous to determine, as a starting time from which the average value of the milking parameter is determined, a point of time after the starting time when the milk flow in step (a) starts. Such a period of time may vary, depending on the milking parameter, between a few seconds and a few tens of seconds.
The average value of the milking parameter is preferably recorded continuously from the starting time. Although continuously recording the average value requires considerable calculation capacity, this results in extremely accurate values.
In an embodiment of a method according to the invention, the method comprises the step of determining and storing the momentary value of the milking parameter. Here by xe2x80x9cstoringxe2x80x9d is meant retaining the value of the milking parameter at least as long as is necessary for processing the value.
Although the value of the milking parameter may be used as such to deactivate the teat cup, it is preferred when a mathematical function is applied to the value of the milking parameter for obtaining a threshold milking parameter value. By selecting the function based on the desires of a manager or farmer the deactivation of the teat cup accordingly can be adapted to his own views.
In an advantageous embodiment of a method according to the invention, the method comprises the step of comparing the momentary value of the milking parameter with the threshold milking parameter value, the step of deactivating the teat cup preferably being carried out when the momentary value of the milking parameter equals or is lower than the threshold milking parameter value. For being insensitive to usually occurring fluctuations or perturbations, the step of deactivating the teat cup is preferably carried out when the momentary value of the milking parameter equals or is lower than the threshold milking parameter value during a period of time. The period of time is preferably adjustable, in particular between approximately two seconds and approximately nine seconds.
The termination of the milking can be accomplished without unfavorably influencing the udder health, in that the method comprises the step of storing in a memory of a computer a number of ranges of average milking parameter values, and of storing in a memory of the computer a respective threshold milking parameter value corresponding with a certain range. For example, with cows, at the following average milk flows: (a) more than 500 ml/min.; (b) between 370 and 500 ml/min.; (c) between 250 and 370 ml/min.; (d) between 170 and 250 ml/min., and (e) less than 170 ml/min., the following threshold milk flows respectively appear to provide good results: (a) 400 ml/min.; (b) 120 ml/min.; (c) 50 ml/min.; (d) 30 ml/min.; and (e) 20 ml/min.
When comparing the average milking parameter value with the ranges stored in the memory demonstrates that the momentary value of the milking parameter value equals or is lower than the threshold milking parameter value corresponding with the average milking parameter value, deactivation of the teat cup can take place.
In an embodiment of a method according to the invention, in which the method comprises the step that, when the average of the threshold milking parameter value equals or is lower than the threshold milking parameter value, deactivation of the teat cup takes place when the momentary value of the milking parameter equals or is lower than the threshold milking parameter, a deactivation of the teat cup takes place each time when the threshold milking parameter has been reached. This prevents the teat from being milked too long.
Based on long research it has been found that a quick deactivation of the teat cup, for example when it is expected that many dairy animals will have to be milked within a short period of time, is carried out correctly when the function consists in dividing the value by three. A deactivation which is not so expedited, in contrast, takes place when the function consists in dividing the value by five. It will be appreciated that the indicated values are thus guide values, which may be deviated based on experience.
The method preferably comprises the step of determining, during obtaining a milk flow, the values of several milking parameters, the deactivation threshold being determined at least partially with the aid of the values of at least two measured milking parameters. Thus it is possible to take into account several values obtained during milking for deactivating the teat cup.
Although by means of the inventive method a deactivation threshold is determined during milking, in some cases it may be advantageous that the method comprises the step of determining, during obtaining a milk flow, the value of at least one milking parameter, and that the deactivation threshold is determined at least partially based on the value of the at least one measured milking parameter and a predetermined milking parameter value which is in particular based on historical data. Accordingly, there is already a deactivation threshold from the beginning of the milking, said deactivation threshold being adapted during milking, according to the invention, with the aid of values of the milking parameters. It is noticed that the deactivation threshold obtained after the milking has ended may be used as a predetermined threshold for the next milking run.
In an embodiment of a method according to the invention the method comprises the step of determining the difference between the momentary value of the milking parameter and the predetermined milking parameter value which is in particular based on historical data. Such a deviation may also be used for determining the deactivation threshold.
It has been found to be in particular practical when during step (a) the value of the momentary milk flow, the value of the average of the milk flow and the value of the momentary electric conductivity of the milk obtained are determined. When the method additionally comprises the step of storing the average, historical electric conductivity of the milk produced by the teat based on historical data, by determining the difference between the momentary electric conductivity and the average, historical electric conductivity, there may be obtained a deactivation threshold which is advantageous with respect to udder health.
Alternatively or additionally an advantageous method according to the invention comprises the step of connecting at least one further teat cup to a further teat of the dairy animal, and the step of determining the electric conductivity of the milk obtained from said further teat.
When the method comprises the step of determining the teat which, in comparison with the other teats, produces at one point of time milk with the lowest electric conductivity, and of determining for every other teat the deviation from the conductivity of the milk produced by that other teat relative to the milk obtained from the teat producing the milk with the lowest conductivity, the step of deactivating the teat cup may be carried out at a point of time depending on the average milk flow and the difference in electric conductivity. As known, the electric conductivity may be used as an indication of possible mastitis, and the ending of the milking may be adapted thereto in this case by taking this electric conductivity into account. At an increased electric conductivity the point of time when the teat cup is deactivated is preferably postponed.
When the measured deviation is greater than a predetermined value, it is preferred when not the exact average milk flow, but a compensated average milk flow is taken as a starting time for deactivating the teat cup. This compensated average milk flow is in particular obtained in an advantageous manner when the method comprises the step of applying a mathematical function to the value of the average milk flow and the difference in electric conductivity for obtaining a compensated threshold milk flow average.
Based on long research it has been found advantageous that, when the deviation is greater than 10%, a function consisting in multiplying the average milk flow by ten and in dividing it by the difference in electric conductivity ensures that deactivation of the teat cup takes place at a point of time which is appropriate with respect to udder health.
Although disconnection of the teat cup may take place simultaneously with deactivation of the teat cup, it is preferred when the step of disconnecting the teat cup is carried out after a predetermined period of time has elapsed after deactivation of the teat cup. Said period of time is in particular adjustable. The period of time is preferably adjustable between approximately two seconds and approximately fifteen seconds.
Although the inventive method is applicable in a conventional, automatic method of milking, the method is in particular advantageous when the automatic milking is carried out by a milking robot. Particularly advantageous is an embodiment of a method according to the invention in which the admission criterion for the milking robot is at least partially adapted based on the value of the milking parameter measured during step (a), or the measured deviation, or both. Although the measured value indicates the momentary situation, it may be nevertheless used for adapting the admission criterion. When the measured value indicates, for example, that the dairy animal is ill, the admission criterion may be altered in such a manner that the sick animal is not admitted. Moreover the measured value may indicate that the dairy animal has developed or changed, so that an adaptation of the admission criterion is desired. Such an adaptation of the criterion on the basis of the measured value may be carried out by a person skilled in the art without further data being required.
The invention further relates to an apparatus for performing the above-described method. The invention particularly relates to an apparatus of the above-described type which is characterized by means for generating a signal that indicate a deactivation threshold wherein the signal is based at least partially on a milking parameter value.